The Pope has branded fake news as the devil's work. What does this mean?

Has Pope Francis missed a fundamental objection to fake news – that it is toxic to democracy?

As a young reporter it was drilled into me that when writing something that would be read by the public, I was on oath to tell the truth. It got me into hot water more than once. Cardinal Heenan in particular urged me not to report things that might damage the good name of the Catholic Church. But failing to report something important is just as much faking the news as making it up.

Pope Francis has branded fake news as the devil's work. The devil is behind it, he tells us, because the devil is the father of lies. We need some distinctions here. The journalist who reports something he knows not to be true, said by somebody else, is not lying. He is doing his job. He might have an obligation, however, to point out the falsity of the claims he has reported.

Thus President Trump was widely reported as claiming that his inauguration crowd in Washington was bigger than President Obama's, and his people branded the media's rebuttal of this claim – despite concrete evidence – as "alternative facts". But wasn't the claim fake news in the first place? "Oh what a tangled web we weave when first we practise to deceive," as Walter Scott warned us. Lies have consequences. One of which, in this case, is the permanent branding of Donald Trump as a liar.

There is no lie where there is no intention to deceive. Plays and novels are works of fiction, not claiming to be believed. But how many people might have been persuaded by the film "Darkest Hour" into believing that Winston Churchill really did descend into the London Underground to listen to what ordinary people thought of the war, as the film describes? Given that most of the narrative is historically true, isn't that bit of it akin to fake news? Or just cinematic licence? In my view it was an artistic misjudgement. The integrity of the film maker is at stake here.

Two sayings on the subject of lying are commonly attributed to Churchill. He is reputed to have said that a lie would be half way round the world before the truth had got its boots on; and that in wartime, the truth needs a bodyguard of lies. The first is not untrue, and not so different from what Pope Francis has just said – though not quite so well. But it wasn't Churchill – fake news, apparently.

The second clearly was him, and refers to the need to deceive an enemy as to one's real intentions prior to battle. Every soldier who donned camouflage has done something similar. A huge fake army was assembled in Kent prior to the Normandy landings, including rubber tanks and cardboard trucks which looked real from the air. It succeeded in persuading the German High Command to leave a substantial force in the Pas-de-Calais area, where they expected the main Allied attack.

Fake news? Yes. A lie? Certainly. But the work of the devil? That is not so clear. But it illustrates the logic of Goebbels' famous dictum, also attributed to Hitler: "If you're going to tell a lie, tell a big one." The full quote is more sinister: “If you tell a lie big enough and keep repeating it, people will eventually come to believe it. The lie can be maintained only for such time as the State can shield the people from the political, economic and/or military consequences of the lie. It thus becomes vitally important for the State to use all of its powers to repress dissent, for the truth is the mortal enemy of the lie..."

One of the powers available for the repression of dissent is to undermine the very possibility of truth in the mind of the public. Eventually, while they may disbelieve everything you tell them, they also disbelieve everything else they hear or read. There is no longer such a thing as real truth, only your truth and my truth – the truth that suits you.

And this is where there is a fundamental objection to fake news that Pope Francis seems to miss. It is toxic to democracy. The basic assumption behind democratic politics is that with a free press, the public can find out the facts, even if politicians are lying to them. They may not be able to do so by themselves, however, which is where journalists come in. And you need lots of journalists, all saying something slightly different but all basically trying to get at the truth.

That is why we must have a plurality of media. The film "The Post"depicts how "The Washington Post" exposed the lies behind the conduct of the Vietnam War in the Pentagon Papers – how hundreds of thousands of lives were recklessly thrown away in a campaign the Pentagon knew all along was unwinnable. The American public was systematically deceived time and again. Whatever we think of Donald Trump's grasp of the truth, this was far worse. Worse, indeed than Watergate, another newspaper exposure of official fake news that shocked the world.

The Pope is right that social media and the internet can work as the enemy of the truth, not least by shutting out contrary opinions and confining people in little bubbles of the likeminded. But social media and the internet have another even more insidious effect. They soak up the advertising revenue that is essential in sustaining the traditional media. So while fake news proliferates through the web, the appropriate corrective – professional journalism, honestly done – is slowly bleeding to death. Truth costs money. Social media has produced numerous internet billionaires. It has also closed down most of the provincial press.

Maybe in the increasingly desperate war against lies and falsehoods it is time we adopted the celebrated Prayer to St Michael the Archangel as our rallying cry: "Defend us in the day of battle, be our safeguard against the wickedness and snares of the devil. May God rebuke him, we humbly pray and do thou, O Prince of the heavenly host, by the power of God, thrust down to hell, Satan and all wicked spirits who wander abroad for the ruin of souls..." Not least by the promotion of fake news.